Protecting the hands from extreme cold or heat has been a difficult problem to solve. The hands, and particularly the fingers, are relatively small and thin extremities. As a result, they are quickly affected by ambient temperatures. The hands can be sheltered from the environment by mittens and gloves, but in either very cold or very warm environments the mittens or gloves must be thick to preserve normal or near-normal body temperature in the hands. Thick mittens or gloves, however, reduce dexterity, and extensive loss of dexterity may be unacceptable for certain activities, such as skiing, race car driving, or work in outer space.
Various means have existed for heating the palm and finger portions of the glove. In the past, electrical resistance circuits powered by batteries have been used to heat a glove. In general, prior electrical systems have been costly, unreliable and not practical due to the limited energy supply of batteries. Electrical battery operated systems do not have sufficient energy to heat the hand of the wearer for extended periods of time. Some prior heating systems for gloves have utilized exothermic packs placed within pockets on the outer surface or shell of the glove. Others have simply dropped the exothermic packs loosely into the glove. The problem with these approaches is that only that portion of the hand immediately adjacent to the pack is heated, and the heat generated is not conducted to the finger areas. Some prior systems have attempted to conduct the heat to the fingers by the use of air ducts or solid conductive materials. These prior methods do not work and are not efficient because air and solid conductive materials do not transfer enough heat from the hand area to the fingers to effectively warm the fingers in cold environments. In addition, prior methods utilizing air ducts and solid conductive materials are very bulky and restrict finger mobility and dexterity as well as being uncomfortable to the wearer.
Poor blood circulation in the hands is sometimes related to the problem of temperature regulation of the hands. Poor blood circulation tends to result in cold hands. Blood circulation can be temporarily improved by manually massaging the hands, but massage normally requires a person to stop the task he or she is doing and, if he or she is wearing gloves, to remove the gloves. This is disruptive to the task and, in very cold or very warm environments, antithetical to the purpose of wearing gloves.